title: Synthesis, crystal structures and DNA-cleaving activities of [Cemp]2[MCl4] (Cemp = N-carbethoxymethyl-1,10-phenanthrolinium, M = Cu(II), Zn(II), Co(II), Ni(II) and Mn(II)).
abstract: N-Carbethoxymethyl-1,10-phenanthrolinium bromide (CempBr) and its five ionic metal complexes, [Cemp]2[MCl4] where M = Cu(II) (1), Zn(II) (2), Co(II) (3), Ni(II) (4) and Mn(II) (5) were synthesized and fully characterized. Complexes 1-5 have similar structures, and consist of isolated [Cemp](+) cations and [MCl4](2-) anions in which there are no obvious interactions between the oxygen or nitrogen donor atoms in [Cemp](+) and the metal center in [MCl4](2-). Agarose gel electrophoresis studies on the cleavage of plasmid pBR322 DNA by complexes 1-5 indicated that complex 1 was capable of efficiently cleaving DNA under physiological conditions, most probably via an oxidative mechanism. Kinetic assay of complex 1 afforded the maximal catalytic rate constant kmax of 0.55 h(-1) and Michaelis constant KM of 47.6 µM, respectively, which gives about 1.5×10(7)-fold rate acceleration over uncatalyzed cleavage of supercoiled DNA. Ethidium bromide displacement experiments indicated that complex 1 had a binding affinity of (1.58±1.12)×10(6) M(-1) toward calf-thymus DNA, 20-100-fold higher than those shown by CempBr and complexes 2-5. The high cleaving efficacy of complex 1 is thought to be due to the efficient catalysis of the copper(II)-coordinated center and the efficient binding of the quaternized 1,10-phenanthroline cation to DNA.
authors.affiliation: School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, PR China.
authors.forename: Ming-Zhen
authors.initials: MZ
authors.lastname: Chen
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Chun-Qiong
authors.initials: CQ
authors.lastname: Zhou
authors.forename: Wei-Er
authors.initials: WE
authors.lastname: Lin
authors.forename: Jin-Xiang
authors.initials: JX
authors.lastname: Chen
authors.forename: Wen-Hua
authors.initials: WH
authors.lastname: Chen
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Jiang
mesh_terms: D003035:Cobalt / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D003300:Copper / Q000737:chemistry; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D053837:DNA Cleavage / Q000187:drug effects; D007700:Kinetics; D008345:Manganese / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry; D010618:Phenanthrolines / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
chemical_list: D056831:Coordination Complexes; D008670:Metals; D010618:Phenanthrolines; D003035:Cobalt; D008345:Manganese; D003300:Copper; D009532:Nickel; D004247:DNA; D015032:Zinc; C025205:1,10-phenanthroline